Albert Girard(1629)MathematicianOther Mathematicians Who Contributed to "Complex Numbers"Bernoulli, Moivre, Euler, Argand, GaussThe term "complex numbers" originated from C.F.Gauss (1831)use the FOIL method or the distributive propertyreplace i^2 with -1Girolamo Cardano(1501-1576)Mathematician and MedicineFirst to introduce complex numbersHe referred complex numbers as a "mental torture" (Ars Magna, Chapter 37)Doubted such expressions such as 5+"square root" of -15Introduced the symbol "i" Established rules for calculating in "C"a+"square root" of -b are solutions impossibles.Multiplying Complex numbersCyclic Pattern of Powers of iQuestions Involving Complex Numbers made up of a combination of real and imaginary numbersreal imaginaryThe Imaginary Unitfirst add or subtract the real parts of the numbersthen add or subtract the imaginary parts of the numbers1. (14 + 7i)